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Introducing the Little Higgs

Martin Schmaltz

TL;DR

This paper addresses the hierarchy problem by arguing that naturalness requires new TeV-scale physics to stabilize the Higgs mass. It introduces the Little Higgs mechanism, where the Higgs is a pseudo-Goldstone boson protected by collective symmetry breaking, delaying quadratic divergences and requiring new partner states to cancel SM loops. Through a Toy Little Higgs model and discussion of symmetry-breaking patterns, it demonstrates how these cancellations can occur without supersymmetry and surveys predicted TeV-scale signatures, including vector-like quarks, new gauge bosons, and extra scalars. The work highlights the experimental implications for the LHC and the role of electroweak precision constraints, positioning Little Higgs theories as a competitive, testable alternative to SUSY for natural electroweak symmetry breaking.

Abstract

Little Higgs theories are an exciting new possibility for physics at TeV energies. In the Standard Model the Higgs mass suffers from an instability under radiative corrections. This ``hierarchy problem'' motivates much of current physics beyond the Standard Model research. Little Higgs theories offer a new and very promising solution to this problem in which the Higgs is naturally light as a result of non-linearly realized symmetries. This article reviews some of the underlying ideas and gives a pedagogical introduction to the Little Higgs. The examples provided are taken from the paper "A Little Higgs from a Simple Group", by D.E. Kaplan and M. Schmaltz.

Introducing the Little Higgs

TL;DR

This paper addresses the hierarchy problem by arguing that naturalness requires new TeV-scale physics to stabilize the Higgs mass. It introduces the Little Higgs mechanism, where the Higgs is a pseudo-Goldstone boson protected by collective symmetry breaking, delaying quadratic divergences and requiring new partner states to cancel SM loops. Through a Toy Little Higgs model and discussion of symmetry-breaking patterns, it demonstrates how these cancellations can occur without supersymmetry and surveys predicted TeV-scale signatures, including vector-like quarks, new gauge bosons, and extra scalars. The work highlights the experimental implications for the LHC and the role of electroweak precision constraints, positioning Little Higgs theories as a competitive, testable alternative to SUSY for natural electroweak symmetry breaking.

Abstract

Little Higgs theories are an exciting new possibility for physics at TeV energies. In the Standard Model the Higgs mass suffers from an instability under radiative corrections. This ``hierarchy problem'' motivates much of current physics beyond the Standard Model research. Little Higgs theories offer a new and very promising solution to this problem in which the Higgs is naturally light as a result of non-linearly realized symmetries. This article reviews some of the underlying ideas and gives a pedagogical introduction to the Little Higgs. The examples provided are taken from the paper "A Little Higgs from a Simple Group", by D.E. Kaplan and M. Schmaltz.

Paper Structure

This paper contains 9 sections, 23 equations, 10 figures.

Table of Contents

  1. Introduction
  2. The hierarchy problem of the Standard Model
  3. Supersymmetry and the hierarchy
  4. SUSY, the only solution to the hierarchy problem?
  5. Introducing the Little Higgs
  6. Higgs as a Pseudo-Goldstone boson
  7. Toy Little Higgs theory
  8. Signatures and Conclusions
  9. Acknowledgments

Figures (10)

  • Figure 1: The most significant quadratically divergent contributions to the Higgs mass in the Standard Model.
  • Figure 2: The fine tuning required to obtain an acceptable Higgs mass in the Standard Model with cut-off 10 TeV.
  • Figure 3: Superpartner diagrams which cancel quadratic divergences of the Standard Model.
  • Figure 4: Higgs loops in the MSSM.
  • Figure 5: Generic Little Higgs Spectrum.
  • ...and 5 more figures